The invention relates to the joining of two plastic components to form a separable form-fitting joint.
When two plastic components are joined to form a permanent integral joint by means of ultrasonic welding or a form-fitting joint by means of ultrasonic riveting, the joining method may result in changes on the surface of the joined workpieces which degrade their appearance. For example, the locations of the joints may become clearly delineated after the joined components are painted. The process of fitting the components together before welding requires that the components be precisely positioned in a way which is difficult to maintain since the components may shift relative to one another. With welded joints, if one component is defective all the components must be replacedxe2x80x94a characteristic which generates unnecessary costs. In addition, the process of welding workpieces requires additional machines and tools.
The object of the invention is to simplify the joining of plastic components while at the same time ensuring the integrity of the surface.
This object is achieved by means of the characterizing features of the first claim. Advantageous embodiments of the invention are claimed in the dependent claims.
According to the invention, the joining of two plastic components is achieved by designing the one plastic component as a base component and the other component as a component to be mounted on the base component, which mounting component forms a form-fitting joint with the latter of the following type: the mounting component, here designated as a cover, is equipped with opposing, pocket-shaped receptacles, as viewed from the mounting direction, called pockets herein, which are formed by tongues on the cover and which accommodate the insertion of flange-shaped edge sections of the base component, called flanges herein. Only one pocket may be provided on each side. In an advantageous feature, especially with regard to the strength of the joint and to the geometry of the edges of the base component, there are provided on the cover at least two pockets on opposing sides in the mounting direction, spaced closely together.
In order to create a joined system between the mounting component, the cover, and the base component, the flanges of the base component must be inserted into the pockets of the cover. To join the two components, there is provided a mounting direction which points away from one anterior end of the base component with one flange in the direction of the opposite posterior end with one flange. To allow the cover to be mounted on the base component, the anterior flange is extended, as viewed from the mounting direction, by at least the width of the posterior flange, and the pockets of the cover associated with the anterior flange of the base component are recessed beyond the width of the anterior flange of the base component by at least the width of the posterior flange. The distance between the bottom of the anterior pockets and the edges of the tongues of the opposing posterior pockets is at least slightly greater than the distance on the base component between the edges of the flanges.
To create the joined system of the two plastic components in the intended manner, the cover is first placed on the base component such that, when viewed from the mounting direction, the anterior flange of the base component comes to rest in front of the cover pockets associated with the flange. When mounting occurs in the mounting direction, this flange is inserted into the pockets.
When the anterior flange has been inserted down to the bottom of the pockets, the opposing pockets have slid so far beyond the posterior flange of the base component that the edge of the posterior base component flange has come to rest in front of openings of the cover pockets associated with it. After the cover is moved back against the mounting direction, the posterior flange of the base component also slides into its associated pockets, thereby securing the cover in a form-fitting manner to the base component.
In one advantageous embodiment of the invention, the base component has ribs which the pocket tongues abut during mounting. Their function is to position the cover on the base component. When the cover is moved back against the mounting direction to create the joined system, the posterior flange of the base component slides under the tongues of the pockets. As this occurs, the pocket tongues abut the ribs located in the posterior section of the base component and position the cover.
In another advantageous embodiment of the invention, the anterior pockets on the cover as viewed from the mounting direction are designed to each have a spring element which is formed from the tongue of the pocket and presses against the rib on the base component. When the cover is mounted, the spring elements immediately press against the rib on the anterior section of the base component and are tensioned. In the mounted condition, the spring elements continue to press against the flange of the base component and thus remain under tension. The result is that the cover is retained in its proper position without the requirement of a permanent joint to connect the two components.
To remove the cover, it is moved far enough in the mounting direction against the springs that the tongues of the posterior pockets release the flange of the base component. After the cover is lifted to the point where the tongues lie above this flange and the cover is moved in the direction opposite the mounting direction, the anterior pockets then also release the anterior flange of the base component, thereby allowing the cover to be lifted off the base component and replaced by another component without any damage being incurred by the base component and cover.